1. Field of the Invention
This invention is directed to a system for indicating wear in vehicle brakes. The system indicates which brakes are worn and troubleshoots itself to indicate if any problems exist in the system.
2. Description of the Related Art
Indicators to sense and report brake lining wear are known in the art. U.S. Pat. Nos. 2,217,176 to Madison; U.S. Pat. No. 3,649,959 to Sakata; U.S. Pat. No. 3,689,880 to McKee et al, U.S. Pat. No. 3,958,445 to Howard et al; U.S. Pat. No. 4,387,789 to Borugian (the most closely related prior art known to the inventor); U.S. Pat. No. 4,606,434 to Vasiilow et al; U.S. Pat. No. 5,403,072 to Kilian et al; and U.S. Pat. No. 5,559,286 to White et al all disclose electrical conductive sensors imbedded in the brake lining of a brake system. These sensors close a circuit when the brake lining wears down to such an extent that the brake drum contacts the sensor, and the closed circuit provides an indication to the vehicle operator that the brake lining has been worn down to a predetermined degree.
These systems allow the operator to be aware of brake lining wearing before the rivets or the metal backing plate holding the linings can damage the brake drum. Thus, brake linings can be replaced before they are dangerously worn or damage is caused to the brake drum.
The prior art systems have drawbacks, however. They do not isolate the problem by indicating which brake is worn. Some of the systems are complex and use expensive parts and parts which are likely to break. Each of the prior art systems known to the inventor may give false positive readings or may fail to give positive readings due to broken connections.